Mother and child wearing their gas masks, Southend, 29 March 1941. [Getty Images]

UNITED KINGDOM : Mother and child wearing their gas masks during gas exercise at Southend, Essex, 29 March 1941. 'A tear gas exercise was held in Southend during shopping hours. Rattles sounded the warning for people to put on their gas masks, and those caught without them had a most unhappy experience'. (Photo by SSPL/Getty Images)

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